1 /* $OpenBSD: sshconnect.c,v 1.215 2009/10/28 16:38:18 reyk Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * Code to connect to a remote host, and to perform the client side of the
7 * login (authentication) dialog.
9 * As far as I am concerned, the code I have written for this software
10 * can be used freely for any purpose. Any derived versions of this
11 * software must be clearly marked as such, and if the derived work is
12 * incompatible with the protocol description in the RFC file, it must be
13 * called by a name other than "ssh" or "Secure Shell".
18 #include <sys/types.h>
21 #include <sys/socket.h>
22 #ifdef HAVE_SYS_TIME_H
23 # include <sys/time.h>
26 #include <netinet/in.h>
27 #include <arpa/inet.h>
52 #include "sshconnect.h"
62 char *client_version_string = NULL;
63 char *server_version_string = NULL;
65 static int matching_host_key_dns = 0;
68 extern Options options;
69 extern char *__progname;
70 extern uid_t original_real_uid;
71 extern uid_t original_effective_uid;
72 extern pid_t proxy_command_pid;
74 static int show_other_keys(const char *, Key *);
75 static void warn_changed_key(Key *);
78 * Connect to the given ssh server using a proxy command.
81 ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
83 char *command_string, *tmp;
86 char *shell, strport[NI_MAXSERV];
88 if ((shell = getenv("SHELL")) == NULL)
91 /* Convert the port number into a string. */
92 snprintf(strport, sizeof strport, "%hu", port);
95 * Build the final command string in the buffer by making the
96 * appropriate substitutions to the given proxy command.
98 * Use "exec" to avoid "sh -c" processes on some platforms
101 xasprintf(&tmp, "exec %s", proxy_command);
102 command_string = percent_expand(tmp, "h", host,
103 "p", strport, (char *)NULL);
106 /* Create pipes for communicating with the proxy. */
107 if (pipe(pin) < 0 || pipe(pout) < 0)
108 fatal("Could not create pipes to communicate with the proxy: %.100s",
111 debug("Executing proxy command: %.500s", command_string);
113 /* Fork and execute the proxy command. */
114 if ((pid = fork()) == 0) {
117 /* Child. Permanently give up superuser privileges. */
118 permanently_drop_suid(original_real_uid);
120 /* Redirect stdin and stdout. */
123 if (dup2(pin[0], 0) < 0)
124 perror("dup2 stdin");
128 if (dup2(pout[1], 1) < 0)
129 perror("dup2 stdout");
130 /* Cannot be 1 because pin allocated two descriptors. */
133 /* Stderr is left as it is so that error messages get
134 printed on the user's terminal. */
137 argv[2] = command_string;
140 /* Execute the proxy command. Note that we gave up any
141 extra privileges above. */
142 execv(argv[0], argv);
148 fatal("fork failed: %.100s", strerror(errno));
150 proxy_command_pid = pid; /* save pid to clean up later */
152 /* Close child side of the descriptors. */
156 /* Free the command name. */
157 xfree(command_string);
159 /* Set the connection file descriptors. */
160 packet_set_connection(pout[0], pin[1]);
161 packet_set_timeout(options.server_alive_interval,
162 options.server_alive_count_max);
164 /* Indicate OK return */
169 * Creates a (possibly privileged) socket for use as the ssh connection.
172 ssh_create_socket(int privileged, struct addrinfo *ai)
175 struct addrinfo hints, *res;
178 * If we are running as root and want to connect to a privileged
179 * port, bind our own socket to a privileged port.
182 int p = IPPORT_RESERVED - 1;
184 sock = rresvport_af(&p, ai->ai_family);
187 error("rresvport: af=%d %.100s", ai->ai_family,
190 debug("Allocated local port %d.", p);
193 sock = socket_rdomain(ai->ai_family, ai->ai_socktype, ai->ai_protocol,
196 error("socket: %.100s", strerror(errno));
198 /* Bind the socket to an alternative local IP address */
199 if (options.bind_address == NULL)
202 memset(&hints, 0, sizeof(hints));
203 hints.ai_family = ai->ai_family;
204 hints.ai_socktype = ai->ai_socktype;
205 hints.ai_protocol = ai->ai_protocol;
206 hints.ai_flags = AI_PASSIVE;
207 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
209 error("getaddrinfo: %s: %s", options.bind_address,
210 ssh_gai_strerror(gaierr));
214 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
215 error("bind: %s: %s", options.bind_address, strerror(errno));
225 timeout_connect(int sockfd, const struct sockaddr *serv_addr,
226 socklen_t addrlen, int *timeoutp)
229 struct timeval tv, t_start;
231 int optval, rc, result = -1;
233 gettimeofday(&t_start, NULL);
235 if (*timeoutp <= 0) {
236 result = connect(sockfd, serv_addr, addrlen);
240 set_nonblock(sockfd);
241 rc = connect(sockfd, serv_addr, addrlen);
243 unset_nonblock(sockfd);
247 if (errno != EINPROGRESS) {
252 fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
254 FD_SET(sockfd, fdset);
255 ms_to_timeval(&tv, *timeoutp);
258 rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
259 if (rc != -1 || errno != EINTR)
270 debug("select: %s", strerror(errno));
273 /* Completed or failed */
275 optlen = sizeof(optval);
276 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
278 debug("getsockopt: %s", strerror(errno));
286 unset_nonblock(sockfd);
289 /* Should not occur */
290 fatal("Bogus return (%d) from select()", rc);
296 if (result == 0 && *timeoutp > 0) {
297 ms_subtract_diff(&t_start, timeoutp);
298 if (*timeoutp <= 0) {
308 * Opens a TCP/IP connection to the remote server on the given host.
309 * The address of the remote host will be returned in hostaddr.
310 * If port is 0, the default port will be used. If needpriv is true,
311 * a privileged port will be allocated to make the connection.
312 * This requires super-user privileges if needpriv is true.
313 * Connection_attempts specifies the maximum number of tries (one per
314 * second). If proxy_command is non-NULL, it specifies the command (with %h
315 * and %p substituted for host and port, respectively) to use to contact
319 ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
320 u_short port, int family, int connection_attempts, int *timeout_ms,
321 int want_keepalive, int needpriv, const char *proxy_command)
325 int sock = -1, attempt;
326 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
327 struct addrinfo hints, *ai, *aitop;
329 debug2("ssh_connect: needpriv %d", needpriv);
331 /* If a proxy command is given, connect using it. */
332 if (proxy_command != NULL)
333 return ssh_proxy_connect(host, port, proxy_command);
335 /* No proxy command. */
337 memset(&hints, 0, sizeof(hints));
338 hints.ai_family = family;
339 hints.ai_socktype = SOCK_STREAM;
340 snprintf(strport, sizeof strport, "%u", port);
341 if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
342 fatal("%s: Could not resolve hostname %.100s: %s", __progname,
343 host, ssh_gai_strerror(gaierr));
345 for (attempt = 0; attempt < connection_attempts; attempt++) {
347 /* Sleep a moment before retrying. */
349 debug("Trying again...");
352 * Loop through addresses for this host, and try each one in
353 * sequence until the connection succeeds.
355 for (ai = aitop; ai; ai = ai->ai_next) {
356 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
358 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
359 ntop, sizeof(ntop), strport, sizeof(strport),
360 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
361 error("ssh_connect: getnameinfo failed");
364 debug("Connecting to %.200s [%.100s] port %s.",
365 host, ntop, strport);
367 /* Create a socket for connecting. */
368 sock = ssh_create_socket(needpriv, ai);
370 /* Any error is already output */
373 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
375 /* Successful connection. */
376 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
379 debug("connect to address %s port %s: %s",
380 ntop, strport, strerror(errno));
386 break; /* Successful connection. */
391 /* Return failure if we didn't get a successful connection. */
393 error("ssh: connect to host %s port %s: %s",
394 host, strport, strerror(errno));
398 debug("Connection established.");
400 /* Set SO_KEEPALIVE if requested. */
401 if (want_keepalive &&
402 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
404 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
406 /* Set the connection. */
407 packet_set_connection(sock, sock);
408 packet_set_timeout(options.server_alive_interval,
409 options.server_alive_count_max);
415 * Waits for the server identification string, and sends our own
416 * identification string.
419 ssh_exchange_identification(int timeout_ms)
421 char buf[256], remote_version[256]; /* must be same size! */
422 int remote_major, remote_minor, mismatch;
423 int connection_in = packet_get_connection_in();
424 int connection_out = packet_get_connection_out();
425 int minor1 = PROTOCOL_MINOR_1;
428 int fdsetsz, remaining, rc;
429 struct timeval t_start, t_remaining;
432 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
433 fdset = xcalloc(1, fdsetsz);
435 /* Read other side's version identification. */
436 remaining = timeout_ms;
438 for (i = 0; i < sizeof(buf) - 1; i++) {
439 if (timeout_ms > 0) {
440 gettimeofday(&t_start, NULL);
441 ms_to_timeval(&t_remaining, remaining);
442 FD_SET(connection_in, fdset);
443 rc = select(connection_in + 1, fdset, NULL,
444 fdset, &t_remaining);
445 ms_subtract_diff(&t_start, &remaining);
446 if (rc == 0 || remaining <= 0)
447 fatal("Connection timed out during "
452 fatal("ssh_exchange_identification: "
453 "select: %s", strerror(errno));
457 len = roaming_atomicio(read, connection_in, &buf[i], 1);
459 if (len != 1 && errno == EPIPE)
460 fatal("ssh_exchange_identification: "
461 "Connection closed by remote host");
463 fatal("ssh_exchange_identification: "
464 "read: %.100s", strerror(errno));
465 if (buf[i] == '\r') {
468 continue; /**XXX wait for \n */
470 if (buf[i] == '\n') {
475 fatal("ssh_exchange_identification: "
476 "No banner received");
478 buf[sizeof(buf) - 1] = 0;
479 if (strncmp(buf, "SSH-", 4) == 0)
481 debug("ssh_exchange_identification: %s", buf);
483 server_version_string = xstrdup(buf);
487 * Check that the versions match. In future this might accept
488 * several versions and set appropriate flags to handle them.
490 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
491 &remote_major, &remote_minor, remote_version) != 3)
492 fatal("Bad remote protocol version identification: '%.100s'", buf);
493 debug("Remote protocol version %d.%d, remote software version %.100s",
494 remote_major, remote_minor, remote_version);
496 compat_datafellows(remote_version);
499 switch (remote_major) {
501 if (remote_minor == 99 &&
502 (options.protocol & SSH_PROTO_2) &&
503 !(options.protocol & SSH_PROTO_1_PREFERRED)) {
507 if (!(options.protocol & SSH_PROTO_1)) {
511 if (remote_minor < 3) {
512 fatal("Remote machine has too old SSH software version.");
513 } else if (remote_minor == 3 || remote_minor == 4) {
514 /* We speak 1.3, too. */
517 if (options.forward_agent) {
518 logit("Agent forwarding disabled for protocol 1.3");
519 options.forward_agent = 0;
524 if (options.protocol & SSH_PROTO_2) {
534 fatal("Protocol major versions differ: %d vs. %d",
535 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
537 /* Send our own protocol version identification. */
538 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s",
539 compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
540 compat20 ? PROTOCOL_MINOR_2 : minor1,
541 SSH_VERSION, compat20 ? "\r\n" : "\n");
542 if (roaming_atomicio(vwrite, connection_out, buf, strlen(buf))
544 fatal("write: %.100s", strerror(errno));
545 client_version_string = xstrdup(buf);
546 chop(client_version_string);
547 chop(server_version_string);
548 debug("Local version string %.100s", client_version_string);
551 /* defaults to 'no' */
553 confirm(const char *prompt)
555 const char *msg, *again = "Please type 'yes' or 'no': ";
559 if (options.batch_mode)
561 for (msg = prompt;;msg = again) {
562 p = read_passphrase(msg, RP_ECHO);
564 (p[0] == '\0') || (p[0] == '\n') ||
565 strncasecmp(p, "no", 2) == 0)
567 if (p && strncasecmp(p, "yes", 3) == 0)
577 * check whether the supplied host key is valid, return -1 if the key
578 * is not valid. the user_hostfile will not be updated if 'readonly' is true.
584 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
585 Key *host_key, int readonly, const char *user_hostfile,
586 const char *system_hostfile)
589 const char *type = key_type(host_key);
590 char *ip = NULL, *host = NULL;
591 char hostline[1000], *hostp, *fp, *ra;
592 HostStatus host_status;
593 HostStatus ip_status;
594 int r, local = 0, host_ip_differ = 0;
596 char ntop[NI_MAXHOST];
598 int len, host_line, ip_line, cancelled_forwarding = 0;
599 const char *host_file = NULL, *ip_file = NULL;
602 * Force accepting of the host key for loopback/localhost. The
603 * problem is that if the home directory is NFS-mounted to multiple
604 * machines, localhost will refer to a different machine in each of
605 * them, and the user will get bogus HOST_CHANGED warnings. This
606 * essentially disables host authentication for localhost; however,
607 * this is probably not a real problem.
609 /** hostaddr == 0! */
610 switch (hostaddr->sa_family) {
612 local = (ntohl(((struct sockaddr_in *)hostaddr)->
613 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
614 salen = sizeof(struct sockaddr_in);
617 local = IN6_IS_ADDR_LOOPBACK(
618 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
619 salen = sizeof(struct sockaddr_in6);
623 salen = sizeof(struct sockaddr_storage);
626 if (options.no_host_authentication_for_localhost == 1 && local &&
627 options.host_key_alias == NULL) {
628 debug("Forcing accepting of host key for "
629 "loopback/localhost.");
634 * We don't have the remote ip-address for connections
635 * using a proxy command
637 if (options.proxy_command == NULL) {
638 if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop),
639 NULL, 0, NI_NUMERICHOST) != 0)
640 fatal("check_host_key: getnameinfo failed");
641 ip = put_host_port(ntop, port);
643 ip = xstrdup("<no hostip for proxy command>");
647 * Turn off check_host_ip if the connection is to localhost, via proxy
648 * command or if we don't have a hostname to compare with
650 if (options.check_host_ip && (local ||
651 strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
652 options.check_host_ip = 0;
655 * Allow the user to record the key under a different name or
656 * differentiate a non-standard port. This is useful for ssh
657 * tunneling over forwarded connections or if you run multiple
658 * sshd's on different ports on the same machine.
660 if (options.host_key_alias != NULL) {
661 host = xstrdup(options.host_key_alias);
662 debug("using hostkeyalias: %s", host);
664 host = put_host_port(hostname, port);
668 * Store the host key from the known host file in here so that we can
669 * compare it with the key for the IP address.
671 file_key = key_new(host_key->type);
674 * Check if the host key is present in the user's list of known
675 * hosts or in the systemwide list.
677 host_file = user_hostfile;
678 host_status = check_host_in_hostfile(host_file, host, host_key,
679 file_key, &host_line);
680 if (host_status == HOST_NEW) {
681 host_file = system_hostfile;
682 host_status = check_host_in_hostfile(host_file, host, host_key,
683 file_key, &host_line);
686 * Also perform check for the ip address, skip the check if we are
687 * localhost or the hostname was an ip address to begin with
689 if (options.check_host_ip) {
690 Key *ip_key = key_new(host_key->type);
692 ip_file = user_hostfile;
693 ip_status = check_host_in_hostfile(ip_file, ip, host_key,
695 if (ip_status == HOST_NEW) {
696 ip_file = system_hostfile;
697 ip_status = check_host_in_hostfile(ip_file, ip,
698 host_key, ip_key, &ip_line);
700 if (host_status == HOST_CHANGED &&
701 (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
706 ip_status = host_status;
710 switch (host_status) {
712 /* The host is known and the key matches. */
713 debug("Host '%.200s' is known and matches the %s host key.",
715 debug("Found key in %s:%d", host_file, host_line);
716 if (options.check_host_ip && ip_status == HOST_NEW) {
718 logit("%s host key for IP address "
719 "'%.128s' not in list of known hosts.",
721 else if (!add_host_to_hostfile(user_hostfile, ip,
722 host_key, options.hash_known_hosts))
723 logit("Failed to add the %s host key for IP "
724 "address '%.128s' to the list of known "
725 "hosts (%.30s).", type, ip, user_hostfile);
727 logit("Warning: Permanently added the %s host "
728 "key for IP address '%.128s' to the list "
729 "of known hosts.", type, ip);
730 } else if (options.visual_host_key) {
731 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
732 ra = key_fingerprint(host_key, SSH_FP_MD5,
734 logit("Host key fingerprint is %s\n%s\n", fp, ra);
740 if (options.host_key_alias == NULL && port != 0 &&
741 port != SSH_DEFAULT_PORT) {
742 debug("checking without port identifier");
743 if (check_host_key(hostname, hostaddr, 0, host_key,
744 ROQUIET, user_hostfile, system_hostfile) == 0) {
745 debug("found matching key w/out port");
751 /* The host is new. */
752 if (options.strict_host_key_checking == 1) {
754 * User has requested strict host key checking. We
755 * will not add the host key automatically. The only
756 * alternative left is to abort.
758 error("No %s host key is known for %.200s and you "
759 "have requested strict checking.", type, host);
761 } else if (options.strict_host_key_checking == 2) {
762 char msg1[1024], msg2[1024];
764 if (show_other_keys(host, host_key))
765 snprintf(msg1, sizeof(msg1),
766 "\nbut keys of different type are already"
767 " known for this host.");
769 snprintf(msg1, sizeof(msg1), ".");
771 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
772 ra = key_fingerprint(host_key, SSH_FP_MD5,
775 if (options.verify_host_key_dns) {
776 if (matching_host_key_dns)
777 snprintf(msg2, sizeof(msg2),
778 "Matching host key fingerprint"
781 snprintf(msg2, sizeof(msg2),
782 "No matching host key fingerprint"
785 snprintf(msg, sizeof(msg),
786 "The authenticity of host '%.200s (%s)' can't be "
788 "%s key fingerprint is %s.%s%s\n%s"
789 "Are you sure you want to continue connecting "
791 host, ip, msg1, type, fp,
792 options.visual_host_key ? "\n" : "",
793 options.visual_host_key ? ra : "",
801 * If not in strict mode, add the key automatically to the
802 * local known_hosts file.
804 if (options.check_host_ip && ip_status == HOST_NEW) {
805 snprintf(hostline, sizeof(hostline), "%s,%s",
808 if (options.hash_known_hosts) {
809 /* Add hash of host and IP separately */
810 r = add_host_to_hostfile(user_hostfile, host,
811 host_key, options.hash_known_hosts) &&
812 add_host_to_hostfile(user_hostfile, ip,
813 host_key, options.hash_known_hosts);
815 /* Add unhashed "host,ip" */
816 r = add_host_to_hostfile(user_hostfile,
818 options.hash_known_hosts);
821 r = add_host_to_hostfile(user_hostfile, host, host_key,
822 options.hash_known_hosts);
827 logit("Failed to add the host to the list of known "
828 "hosts (%.500s).", user_hostfile);
830 logit("Warning: Permanently added '%.200s' (%s) to the "
831 "list of known hosts.", hostp, type);
834 if (readonly == ROQUIET)
836 if (options.check_host_ip && host_ip_differ) {
838 if (ip_status == HOST_NEW)
839 key_msg = "is unknown";
840 else if (ip_status == HOST_OK)
841 key_msg = "is unchanged";
843 key_msg = "has a different value";
844 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
845 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
846 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
847 error("The %s host key for %s has changed,", type, host);
848 error("and the key for the corresponding IP address %s", ip);
849 error("%s. This could either mean that", key_msg);
850 error("DNS SPOOFING is happening or the IP address for the host");
851 error("and its host key have changed at the same time.");
852 if (ip_status != HOST_NEW)
853 error("Offending key for IP in %s:%d", ip_file, ip_line);
855 /* The host key has changed. */
856 warn_changed_key(host_key);
857 error("Add correct host key in %.100s to get rid of this message.",
859 error("Offending key in %s:%d", host_file, host_line);
862 * If strict host key checking is in use, the user will have
863 * to edit the key manually and we can only abort.
865 if (options.strict_host_key_checking) {
866 error("%s host key for %.200s has changed and you have "
867 "requested strict checking.", type, host);
872 * If strict host key checking has not been requested, allow
873 * the connection but without MITM-able authentication or
876 if (options.password_authentication) {
877 error("Password authentication is disabled to avoid "
878 "man-in-the-middle attacks.");
879 options.password_authentication = 0;
880 cancelled_forwarding = 1;
882 if (options.kbd_interactive_authentication) {
883 error("Keyboard-interactive authentication is disabled"
884 " to avoid man-in-the-middle attacks.");
885 options.kbd_interactive_authentication = 0;
886 options.challenge_response_authentication = 0;
887 cancelled_forwarding = 1;
889 if (options.challenge_response_authentication) {
890 error("Challenge/response authentication is disabled"
891 " to avoid man-in-the-middle attacks.");
892 options.challenge_response_authentication = 0;
893 cancelled_forwarding = 1;
895 if (options.forward_agent) {
896 error("Agent forwarding is disabled to avoid "
897 "man-in-the-middle attacks.");
898 options.forward_agent = 0;
899 cancelled_forwarding = 1;
901 if (options.forward_x11) {
902 error("X11 forwarding is disabled to avoid "
903 "man-in-the-middle attacks.");
904 options.forward_x11 = 0;
905 cancelled_forwarding = 1;
907 if (options.num_local_forwards > 0 ||
908 options.num_remote_forwards > 0) {
909 error("Port forwarding is disabled to avoid "
910 "man-in-the-middle attacks.");
911 options.num_local_forwards =
912 options.num_remote_forwards = 0;
913 cancelled_forwarding = 1;
915 if (options.tun_open != SSH_TUNMODE_NO) {
916 error("Tunnel forwarding is disabled to avoid "
917 "man-in-the-middle attacks.");
918 options.tun_open = SSH_TUNMODE_NO;
919 cancelled_forwarding = 1;
921 if (options.exit_on_forward_failure && cancelled_forwarding)
922 fatal("Error: forwarding disabled due to host key "
926 * XXX Should permit the user to change to use the new id.
927 * This could be done by converting the host key to an
928 * identifying sentence, tell that the host identifies itself
929 * by that sentence, and ask the user if he/she whishes to
930 * accept the authentication.
934 fatal("internal error");
938 if (options.check_host_ip && host_status != HOST_CHANGED &&
939 ip_status == HOST_CHANGED) {
940 snprintf(msg, sizeof(msg),
941 "Warning: the %s host key for '%.200s' "
942 "differs from the key for the IP address '%.128s'"
943 "\nOffending key for IP in %s:%d",
944 type, host, ip, ip_file, ip_line);
945 if (host_status == HOST_OK) {
947 snprintf(msg + len, sizeof(msg) - len,
948 "\nMatching host key in %s:%d",
949 host_file, host_line);
951 if (options.strict_host_key_checking == 1) {
953 error("Exiting, you have requested strict checking.");
955 } else if (options.strict_host_key_checking == 2) {
956 strlcat(msg, "\nAre you sure you want "
957 "to continue connecting (yes/no)? ", sizeof(msg));
975 /* returns 0 if key verifies or -1 if key does NOT verify */
977 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
982 if (options.verify_host_key_dns &&
983 verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
985 if (flags & DNS_VERIFY_FOUND) {
987 if (options.verify_host_key_dns == 1 &&
988 flags & DNS_VERIFY_MATCH &&
989 flags & DNS_VERIFY_SECURE)
992 if (flags & DNS_VERIFY_MATCH) {
993 matching_host_key_dns = 1;
995 warn_changed_key(host_key);
996 error("Update the SSHFP RR in DNS with the new "
997 "host key to get rid of this message.");
1002 /* return ok if the key can be found in an old keyfile */
1003 if (stat(options.system_hostfile2, &st) == 0 ||
1004 stat(options.user_hostfile2, &st) == 0) {
1005 if (check_host_key(host, hostaddr, options.port, host_key,
1006 RDONLY, options.user_hostfile2,
1007 options.system_hostfile2) == 0)
1010 return check_host_key(host, hostaddr, options.port, host_key,
1011 RDRW, options.user_hostfile, options.system_hostfile);
1015 * Starts a dialog with the server, and authenticates the current user on the
1016 * server. This does not need any extra privileges. The basic connection
1017 * to the server must already have been established before this is called.
1018 * If login fails, this function prints an error and never returns.
1019 * This function does not require super-user privileges.
1022 ssh_login(Sensitive *sensitive, const char *orighost,
1023 struct sockaddr *hostaddr, struct passwd *pw, int timeout_ms)
1026 char *server_user, *local_user;
1028 local_user = xstrdup(pw->pw_name);
1029 server_user = options.user ? options.user : local_user;
1031 /* Convert the user-supplied hostname into all lowercase. */
1032 host = xstrdup(orighost);
1033 for (cp = host; *cp; cp++)
1035 *cp = (char)tolower(*cp);
1037 /* Exchange protocol version identification strings with the server. */
1038 ssh_exchange_identification(timeout_ms);
1040 /* Put the connection into non-blocking mode. */
1041 packet_set_nonblocking();
1044 /* authenticate user */
1046 ssh_kex2(host, hostaddr);
1047 ssh_userauth2(local_user, server_user, host, sensitive);
1049 ssh_kex(host, hostaddr);
1050 ssh_userauth1(local_user, server_user, host, sensitive);
1056 ssh_put_password(char *password)
1061 if (datafellows & SSH_BUG_PASSWORDPAD) {
1062 packet_put_cstring(password);
1065 size = roundup(strlen(password) + 1, 32);
1066 padded = xcalloc(1, size);
1067 strlcpy(padded, password, size);
1068 packet_put_string(padded, size);
1069 memset(padded, 0, size);
1074 show_key_from_file(const char *file, const char *host, int keytype)
1080 found = key_new(keytype);
1081 if ((ret = lookup_key_in_hostfile_by_type(file, host,
1082 keytype, found, &line))) {
1083 fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1084 ra = key_fingerprint(found, SSH_FP_MD5, SSH_FP_RANDOMART);
1085 logit("WARNING: %s key found for host %s\n"
1087 "%s key fingerprint %s.\n%s\n",
1088 key_type(found), host, file, line,
1089 key_type(found), fp, ra);
1097 /* print all known host keys for a given host, but skip keys of given type */
1099 show_other_keys(const char *host, Key *key)
1101 int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
1104 for (i = 0; type[i] != -1; i++) {
1105 if (type[i] == key->type)
1107 if (type[i] != KEY_RSA1 &&
1108 show_key_from_file(options.user_hostfile2, host, type[i])) {
1112 if (type[i] != KEY_RSA1 &&
1113 show_key_from_file(options.system_hostfile2, host, type[i])) {
1117 if (show_key_from_file(options.user_hostfile, host, type[i])) {
1121 if (show_key_from_file(options.system_hostfile, host, type[i])) {
1125 debug2("no key of type %d for host %s", type[i], host);
1131 warn_changed_key(Key *host_key)
1134 const char *type = key_type(host_key);
1136 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1138 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1139 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1140 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1141 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1142 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1143 error("It is also possible that the %s host key has just been changed.", type);
1144 error("The fingerprint for the %s key sent by the remote host is\n%s.",
1146 error("Please contact your system administrator.");
1152 * Execute a local command
1155 ssh_local_cmd(const char *args)
1161 if (!options.permit_local_command ||
1162 args == NULL || !*args)
1165 if ((shell = getenv("SHELL")) == NULL)
1166 shell = _PATH_BSHELL;
1170 debug3("Executing %s -c \"%s\"", shell, args);
1171 execl(shell, shell, "-c", args, (char *)NULL);
1172 error("Couldn't execute %s -c \"%s\": %s",
1173 shell, args, strerror(errno));
1175 } else if (pid == -1)
1176 fatal("fork failed: %.100s", strerror(errno));
1177 while (waitpid(pid, &status, 0) == -1)
1179 fatal("Couldn't wait for child: %s", strerror(errno));
1181 if (!WIFEXITED(status))
1184 return (WEXITSTATUS(status));